Figure 1

The frequency of arched-back nursing (ABN) of the pups as displayed by the mother rats across postnatal days (PND) 2–8. The frequency of ABN by the mother was observed daily during four observation periods (0700, 1300, 1700 and 2000 hours) in litters subjected daily to 3 h maternal separation (MS180, n=13) or a control treatment (MS0, n=12). Data show mean±s.e.m. percentage of time. *P<0.05 for MS180 versus MS0.